The present invention relates to a thin film magnetic head for writing and reading information at a high density in and out of a hard disk drive (HDD) or the like magnetic recording medium. It also contains method for fabricating the thin film magnetic head.
In order to meet the growing needs for increasing the recording capacity in a hard disk drive and the like magnetic recording medium, intensive efforts are being made to increase the recording density.
A conventional thin film magnetic head is described in the following with reference to drawings.
A thin film magnetic head as shown in FIG. 46, or a so-called MR inductive complex head, is one of the popular writing/reading heads used in the HDDs. A first combined structure 4605, which is constituted with a magneto-resistive (MR) film, or a giant magneto-resistive (GMR) film 4602, formed on a lower shield section 4601, a hard film 4603 formed at both sides of the film 4602, and an electrode 4604 formed above the hard film 4603 in the form of a film stretching towards rear portion, is reading section for reproducing signals stored in a magnetic recording medium. A second combined structure 4612, which is constituted with lower magnetic pole formed of a shared shield section 4606 and a lower write chip section 4607, a coil 4608 formed above with an insulation layer (not shown) interposed, and upper magnetic pole formed of an upper write chip 4609 and a yoke 4610, the lower write chip 4607 and the upper write chip 4609 being disposed opposing to each other, is writing section for writing signals in a magnetic recording medium. The xe2x80x9ccommonxe2x80x9d shield 4606 is so named because it is part of the lower magnetic pole of the writing section, at the same time it functions as shield for the reading section.
The second combined structure 4612, or the writing section, is described next referring to FIG. 47. On the shared shield section 4701, the lower write chip section 4702, a gap section 4703, an upper write chip section 4704, a first layer coil 4705, a second layer coil 4706, and a yoke section 4707 are stacked in the order by a sputtering or the like thin film forming process. The lower write chip section 4702 and the upper write chip section 4704 are generally formed with a magnetic material having a high saturation magnetic flux density (Bs), while the yoke section 4707 is generally formed with a magnetic material having a high resistivity (xcfx81). The gap section 4703 is formed with SiO2 or the like insulating material, the coils 4705, 4706 are formed with a copper or the like conductive material. A space formed by the opposing shared shield section 4701 and yoke section 4707, in which the coils 4705 and 4706 are disposed, is filled with an insulating material 4708. The coils 4705, 4706 are winding around the yoke section 4707 in the rear portion where it makes contact with the shared shield section 4701. The coils 4705, 4706 generate magnetic fields, when provided with electricity, in the outside of the gap section 4703 to write signals in a magnetic recording medium. Hereunder, the writing section will be referred to as thin film magnetic head.
In the conventional thin film magnetic head, where the upper write chip section and the yoke section, these constitute the upper magnetic pole, are making contact only in a region of the head track width and the head gap depth, the upper write chip section is not supplied with sufficient magnetic flux from the yoke section. Even if the saturation magnetic flux density (Bs) is enhanced with the upper write chip section and the lower write chip section it is difficult for the writing magnetic fields to go stronger because of influence by the magnetic saturation. Problem is that the writing magnetic fields are not strong enough for recording signals in a high coercive force (Hc) recording medium, which has been making a significant advance for high density recording. While on the other hand, if the head track width is made smaller for the higher recording density, the contact region between the upper write chip section and the yoke section goes smaller, and the recording magnetic fields eventually go even weaker. Thus the effectiveness on the high Hc recording medium is retarded.
A thin film magnetic head of the present invention comprises a lower magnetic pole including a shared shield section and a lower write chip section made of a high Bs magnetic layer disposed on the upper surface of the shared shield section at the tip end portion; a gap section formed on the upper surface of the lower write chip section; an upper magnetic pole including an upper write chip section made of a high Bs magnetic layer disposed on the gap section, opposing to the lower write chip section, and a yoke section made of a high xcfx81 magnetic layer that makes contact in a part with the lower magnetic pole while coupled at the tip end portion with the upper write chip section; and a coil winding around going through a space formed by the opposing magnetic poles, in a region between the both magnetic poles"" contact area and the upper write chip section, and a space behind the yoke section. Wherein, the upper write chip section is longer than the lower write chip section in the direction of the depth.
Under the above-described configuration, where the upper write chip section is longer than the lower write chip section, area of contact between the upper write chip section and the yoke section can be increased. Therefore, strong recording magnetic fields are made available with sufficient supply of magnetic flux from the yoke section. Furthermore, the yoke section of the upper magnetic pole made of a high xcfx81 magnetic layer provides favorable high frequency characteristics.
A preferred example of the thin film magnetic head in accordance with the present invention is that the width of yoke is made greater in a region coupling with the upper write chip section than the head track width formed by the upper write chip section and the lower write chip section. The greater width of the yoke section, which is formed of the high xcfx81 magnetic layer, eases the magnetic saturation at the tip end of yoke, and a plenty amount of magnetic flux is supplied to the tip end of the yoke section. Thus, strong recording magnetic fields are made available through the upper write chip section to an improved recording efficiency.
Other exemplary thin film magnetic head of the present invention is that the end surface at the tip end of the yoke section coupled to the upper write chip section is locating inward relative to the end face of the upper write chip section. This configuration suppresses the fringe at the head gap section, and enables to reduce the track pitch for an increased surface recording density.
Still other example of thin film magnetic head is that it is provided with a shared shield section that has a hollow in an area corresponding to the coil. This configuration reduces inductance of a magnetic pole formed by the upper magnetic pole and the lower magnetic pole, and the high frequency characteristics may be improved.
A method for fabricating a thin film magnetic head of the present invention comprises a first step for forming an insulating layer on the flat upper surface of a shared shield section; a second step of dry-etching the insulating layer for exposing the upper surface of the shared shield section so that an edge line of the insulating layer after the dry-etching assumes a straight line shape; a third step for forming a lower high Bs magnetic layer on the exposed upper surface of the shared shield section and the upper surface of the insulating layer; a fourth step of polishing the upper surface of the insulating layer and the upper surface of the lower high Bs magnetic layer to be in parallel with the upper surface of the shared shield section; a fifth step for forming a gap layer on the upper surfaces of the lower high Bs magnetic layer and the insulating layer polished at the fourth step; a sixth step for forming an upper high Bs magnetic layer on the upper surface of the gap layer; a seventh step for forming a structure having a specific head track width, by dry-etching the insulating layer, the lower high Bs magnetic layer, the gap layer and the upper high Bs magnetic layer altogether at once; an eighth step for forming an insulating underlayer over the exposed upper surface of the shared shield section and the upper surface, the left and the right sides and the front and the rear surfaces of the structure; a ninth step for forming a first coil layer by plating on the upper surface of the insulating underlayer behind the structure so that the coil thickness approximately matches the upper surface of the insulating underlayer on the structure; a tenth step for forming a lower insulating layer over the first coil layer; an eleventh step of polishing the whole area flat in parallel to the upper surface of the shared shield section so that the upper high Bs magnetic layer of the structure and the first coil layer are exposed; a twelfth step of dry-etching for removing the lower insulating layer and the insulating underlayer so that the shared shield section is exposed at the central area of the first coil layer; a thirteenth step for forming an intermediary insulating layer using a photoresist so that the exposed upper high Bs magnetic layer and the exposed area of the shared shield section exposed at the twelfth step are kept in their exposed state and a hole is provided on the innermost winding of the first coil layer; a fourteenth step of plating a second coil layer on the intermediary insulating layer so that the innermost winding locates on the hole provided on the innermost winding of the first coil layer; a fifteenth step for forming an upper insulating layer using a photoresist so that the second coil layer is covered while the exposed upper high Bs magnetic layer and the exposed state of the shared shield section are approximately maintained as they are; a sixteenth step of forming a high xcfx81 magnetic layer on the upper surface of the body provided through the fifteenth step; and a seventeenth step for forming a yoke section using a dry-etching process so that the width of the high xcfx81 magnetic layer is identical to, or greater than, width of the upper high Bs magnetic layer in a region making contact with the upper high Bs magnetic layer, while the width in the rear portion is greater than that of the upper high Bs magnetic layer.
With the above-described fabricating method, where the lower high Bs magnetic layer, the gap layer and the upper high Bs magnetic layer are stacked one after the other in the order, and then these layers altogether undergo a process step for forming a certain track width, a narrow track width is made available at a high precision level. This enables to make the track pitch narrower, and makes a significant contribution to an improved surface recording density. Furthermore, it is easy to provide an upper high Bs magnetic layer that is longer than a lower high Bs magnetic layer, because in the above-described fabricating method the lower high Bs magnetic layer and the insulating layer are disposed in series and the upper high Bs magnetic layer is formed on it with a gap layer interposed. Thus the contact area with a yoke section is increased, and a thin film magnetic head of strong recording magnetic fields is implemented.